Muscarinic receptor agonists

ABSTRACT

A compound of Formula (III):                    
     wherein X is a linkage independently selected from (CH 2 ) 12  or (CH 2 CH 2 ) 4 O 3  and wherein R 3  is independently selected from H, CH 2 CH 3 , COCH 3  or                    
     and acid addition salts, solvates and hydrates thereof. The compounds have unusually high affinity for muscarinic receptors, and exhibit agonist activity useful in the treatment of neurological and other disorders, in which stimulating cholinergic activity is desirable.

RELATED APPLICATIONS

The present invention is a division of Ser. No. 09/772,143, Jan. 29,2001, now U.S. Pat. No. 6,376,675 which is a continuation-in-part ofU.S. Ser. No. 09/629,029 filed Jul. 31, 2000, now U.S. Pat. No.6,369,081 which is a divisional application of U.S. Ser. No. 09/236,030filed Jan. 22, 1999, now U.S. Pat. No. 6,096,767 issued Aug. 1, 2000.

FIELD OF THE INVENTION

This invention relates to muscarinic receptor ligands with agonistactivity. More particularly, this invention relates to compounds basedon the tetrahydropyridyl moiety that have unusually high affinity formuscarinic receptors, and exhibit agonist activity useful in thetreatment of neurological and other disorders, in which stimulatingcholinergic activity is desirable.

BACKGROUND OF THE INVENTION

Recent advances have been made in the understanding of the cholinergicnervous system and the receptors therein. Cholinergic receptors areproteins embedded in the cell membrane that respond to the chemicalacetylcholine. Cholinergic receptors are subdivided into the nicotinicand muscarinic receptor families, and muscarinic receptors represent afamily of five subtypes.

Muscarinic receptors mediate a variety of physiological responses to theneurotransmitter acetylcholine in the central and peripheral nervoussystems. M₁ muscarinic receptors play a role in learning and memoryfunction in the brain and regulate gastric acid secretion in thestomach. M₂ receptors regulate acetylcholine release in the centralnervous system and control cardiac muscle contraction. Acetylcholinestimulates smooth muscle contraction in a variety of tissues andpromotes secretion from exocrine glands. These effects are mediated byM₃ receptors. Though less well characterized pharmacologically, M₄receptors appear to play a role in the perception of pain, and M₅receptors may regulate dopaminergic activity in the brain.

It has been suggested that compounds capable of mimicking the action ofacetylcholine at these receptors would be useful in treatingpathological conditions involving imbalances in these cholinergicpathways. Despite the wealth of knowledge about muscarinic receptorsubtypes, relatively few selective ligands are available to characterizemuscarinic receptor subtypes. Consequently, the tendency for ligands tobind indiscriminately to muscarinic receptor subtypes has made difficultthe development of drugs that are muscarinic receptor subtype selective.

In view of the foregoing, it would be desirable to provide suchcompounds, particularly so side effects are minimized during treatmentof the conditions noted above. It is an object of the present inventionto provide compounds having muscarinic receptor affinity and activity.It is another object of the present invention to provide compoundshaving improved muscarinic receptor selectivity profiles. It is anotherobject of the present invention to provide pharmaceutical compositioncomprising compounds of the present invention, as active ingredients.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided acompound of Formula I:

wherein R is a linkage independently selected from (CH₂)₁₂ or(CH₂CH₂)₄O₃, i.e., CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂—; and acid additionsalts, solvates and hydrates thereof.

According to another aspect of the present invention, there is provideda compound of the Formula III:

wherein X and R are

IIIa=CDD-0297-A: X=(CH₂)₁₂, R₁=R₂=R₃=H

IIIb=CDD-0299-A: X=(CH₂)₁₂, R₁=R₂=H, R₃=COCH₃

IIIc=CDD-0300-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=R₂=R₃=H

IIId=CDD-0301-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=R₂=R₃=CH₂CH₃

IIIe=CDD-0303-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=R₂=H, R₃=COCH₃

IIIf=CDD-0304-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=H, R₂=R₃=

 and acid addition salts, solvates and hydrates thereof.

According to another aspect of the present invention there is provided apharmaceutical composition comprising compounds of Formula (I) or (III)and a pharmaceutically acceptable carrier.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One aspect of the invention relates to bis-alkyloxy-1,2,5-thiadiazolederivatives of 1,2,5,6-tetrahydropyridine that bind to and activatemuscarinic receptors. The compounds incorporate two functionalmuscarinic agonists into the same molecule with an alkyloxy linkage.More particularly, the present invention is directed to compounds ofFormula (I):

wherein R is a linkage independently selected from (CH₂)₁₂ or(CH₂CH₂)₄O₃, and acid addition salts, solvates and hydrates thereof.

According to another aspect of the present invention, there is provideda compound of the Formula III:

wherein X and R are

IIIa=CDD-0297-A: X=(CH₂)₁₂, R₁=R₂=R₃=H

IIIb=CDD-0299-A: X=(CH₂)₁₂, R₁=R₂=H, R₃=COCH₃

IIIc=CDD-0300-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=R₂=R₃=H

IIId=CDD-0301-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=R₂=R₃=CH₂CH₃

IIIe=CDD-0303-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=R₂=H, R₃=COCH₃

IIIf=CDD-0304-A: X=(CH₂CH₂OCH₂CH₂OCH₂CH₂OCH₂CH₂), R₁=H, R₂=R₃=

 and acid addition salts, solvates and hydrates thereof.

The compounds of Formula (I),2,2′-bis-{[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yloxy]ethyloxy}-diethylether and1,12-bis-[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yloxy]-dodecane,exhibit very high affinity for muscarinic receptors as compared to theparent compound xanomeline. In addition, the compounds appear tointeract with multiple M₂ receptors expressed in A9 L cells. It isbelieved that compounds of Formula (I) may act as agonists at muscarinicreceptors coupled to the inhibition of adenylyl cyclase activity.

TABLE 1 Ligand/ M1 Receptors % High M2 Receptors K_(h) Linkage K₁ (nM)affinity (pM) K₁ (nM) Xanome-  82 ± 6.7 26 ± 8.5 23 ± 16 32 ± 12 line(CH₂)₆ 0.61 ± 0.18 18 ± 4.5 0.0086 ± 0.0069  0.28 ± 0.020 (CH₂)₈  0.19 ±0.040 40 ± 11 58 ± 56 0.38 ± 0.15 (CH₂)₁₀ 0.23 ± 0.10 26 ± 3.1 3.1 ± 2.4 0.23 ± 0.040 (CH₂₋  0.12 ± 0.057 — — — CH₂)₄O₃

It was heretofore believed that as the length of the alkoxy chainincreases agonist activity decreases. As reported in the Journal ofMedicinal Chemistry, 1993, Vol. 36, No. 7, pages 843-844, increasing thelength of the 3-alkyl chain on the 1,2,4-oxadiazole ring of1,4,5,6-tetrahydropyrimidine dramatically decreased activity in thephosphoinositide metabolism assay. Again these data are consistent withsimilar observations in 1,2,4-oxadiazole derivatives of1,2,5,6-tetrahydro-1-methylpyridine and quinuclidine where increasingthe length of the 3-alkyl substituent led to compounds with higheraffinity yet lower agonist activity. As shown in Tables 1 and 2, it hasbeen surprisingly found that compounds of Formula I with increasingalkoxy chains displayed M₁ agonist efficacy comparable to xanomeline,yet with higher potency and higher affinity for M₁ receptors.

The receptor binding properties and agonist activity of bis-thiadiazolederivatives, (Formula (II)), at M₁ muscarinic receptors expressed in A9L cells is provided below in Table 2. PI metabolism represents thepercentage stimulation above basal levels at 100 μM expressed relativeto the carbachol response (100%). Full dose-response curves wereobtained for a few compounds. The data represents the mean (±s.e.m.)from two to five assays for each compound.

wherein R is a linkage independently selected from (CH₂)₂, (CH₂)₃,(CH₂)₄, (CH₂)₅, (CH₂)₆, (CH₂)₇, (CH₂)₈, (CH₂)₉, (CH₂)₁₀, (CH₂)₁₂ and(CH₂CH₂)₄O₃.

TABLE 2 Pl Compound/Linkage metabolism EC₅₀ (μM) S_(max) Xanomeline n.d.5.7 ± 2.3 180 ± 24% (CH₂)₂ 50 ± 14% — — (CH₂)₃ 21 ± 2.6% — — (CH₂)₄ 21 ±1.9 — — (CH₂)₅ −1.0 ± 1.8% — — (CH₂)₆ 18 ± 0.06% — — (CH₂)₇ −3.0 ± 3.4%— — (CH₂)₈ 8.2 ± 1.4% — — (CH₂)₉ 27 ± 6.2% 0.72 ± 0.37 140 ± 34% (CH₂)₁₀76 ± 11% — — (CH₂)₁₂ 84 ± 9.9 0.34 ± 0.19 190 ± 61% (CH₂CH₂)₄O₃ — 0.0085± 0.0012 250 ± 36%

The compounds of Formula III are based on the Formula I bivalentxanomeline derivatives described in the Example 1. The Formula Icompounds exhibited high affinity and receptor activity, but theirutility was limited by poor oral bioavailability and low CNSpenetration, which is believed to be due to the large size and presenceof two tertiary amines, which are both positively charged atphysiological pH.

The compounds of Formula III incorporate hydrogen bonding elements asester isosteres (i.e., alcohols, esters, 1,2,5-thiadiazoles) at the endof an alkyl or alkyloxy linking group as shown below. The compounds lacka second tetrahydropyridine moiety. Examples of the compounds of FormulaIII are shown in Table 3. The compounds of Formula III bind to M₁muscarinic receptors and activate phosphoinositide metabolism in A9 Lcells. The compounds of Formula III exhibit increased bioavailabilityand improved CNS penetration, as compared to the compounds of Formula I.

TABLE 3 Muscarinic Agonists Muscarinic Phosphoinositide receptormetabolism binding S_(max) Compound Structure K_(i) value EC₅₀CDD-0297-A

16 ± 3.1 nM 250 ± 28% 2.6 ± 0.18 μM CDD-0299-A

16 ± 13 nM 280 ± 17% 3.4 ± 1.6 μM CDD-0300-A

150 ± 42 nM 240 ± 64% 0.71 ± 0.17 μM CDD-0301-A

570 ± 220 nM 420 ± 220% 29 ± 23 μM CDD-0303-A

280 ± 130 nM n.d. CDD-0304-A

38 ± 23 nM 600 ± 56% 0.064 ± 0.016 μM

The compounds of Formulae (I) and (III) are preferably isolated insubstantially pure form.

The binding profiles of the compounds of Formulae (I) and (III) indicatetheir utility as pharmaceuticals useful for the treatment of variousconditions in which the use of a muscarinic receptor ligand isindicated. More particularly, the compounds of Formulae (I) and (III)have been found to mimic acetylcholine function via an action atmuscarinic receptors and are therefore of potential use in the treatmentof pain, Alzheimer's disease and other disorders involving cholinergicdeficits. Furthermore, it has been found that the inclusion ofheteroatoms in the alkyl chain improves the water solubility of thecompounds. In addition, agonist activity is enhanced relative to thestraight chain derivatives.

The present invention also provides pharmaceutical compositions, whichcomprise compounds of Formulae (I) and (III) or pharmaceuticallyacceptable salts thereof, and pharmaceutically acceptable carriers. Thepharmaceutical composition may be in the form of patches, tablets,capsules, powders, granules, lozenges, suppositories, reconsititutablepowders or liquid preparations such as oral or sterile parenteralsolutions or suspensions. The pharmaceutical composition includescompounds of Formulae (I) and (III) of a pharmaceutically acceptablelevel of purity excluding normal pharmaceutical additives such asdiluents and carriers, and including no material considered toxic atnormal dosage levels. A pharmaceutically acceptable level of purity willgenerally be at least 90% excluding normal pharmaceutical additives,preferably 95%; more preferably 97% and still more preferably 99%.

Sauerbeg et al., Journal Medicinal Chemistry, 1992, Vol. 35, page 2274,reported the synthesis and SAR of potent ligands of M₁ receptors basedon the 1,2,5-thiadiazolyl-tetrahydropyridine moieties. In accordancewith the present invention, is was found that if two1,2,5-thiadiazolyl-tetrahydropyridine moieties are tethered by spacersof varied length and rigidity, in a single structure, the bindingaffinity of the resultant bis ligands is enhanced. By varying the lengthof the alkyl chain and also replacing some of the carbons withheteroatoms such as N, O or S, structure activity relationships isestablished. The two moieties in the same molecule may either bind inthe pockets of two proximal receptors or in two pockets of the samereceptor molecule.

The compounds of Formulae (I) and (III) can be prepared as describedbelow.

The following is a detailed example of a preferred process to preparecompounds of Formulae (I) and (III). It will be understood that thefollowing examples are not intended to limit the scope of the invention.

EXAMPLE 1

3-(3-chloro-1,2,5-thiadiazol-4-yl-pyridine (compound 1) was synthesizedfrom 3-pyridinecarboxaldehyde following, except with slightmodification, from the published procedure as provided in Sauerberg etal, Journal Medicinal Chemistry, 1992, Vol. 35, Page 2274.3-(3-Chloro-1,2,5-thiadiazol-4-yl)pyridine was reacted with a diol(compound 2, wherein n=6, 7, 8, 9, 10 or 12) in the presence of sodiumhydride in refluxing THF to yieldbis[3-(pyridin-3-yl)-1,2,5-thiadiazol-4-yl]alkyl-diethers (compound 3,wherein n=6, 7, 8, 9, 19 or 12) in 75-90% yield. These diethers weretreated with excess methyl iodide in acetone or chloroform to givebis-quaternary ammonium iodides (compound 4, wherein n=6, 7, 8, 9, 10 or12) in 96-100% yield. The quaternary salts were then treated with 5equivalents of sodium borohydride in a mixture of methanol andchloroform to yield the compounds 5, wherein n=6, 7, 8, 9, 10 or 12 in50-60% yield. Dry hydrogen chloride gas was then bubbled through themethanolic solution of compounds 5 at 0° C. to give compounds 6, whereinn=6, 7, 8, 9, 10 or 12 in 95-100% yield.

In view of the detailed description provided herein, it will beappreciated by one skilled in the art that the above bis-ligandmethodology can include, but not be limited to, other known andpotential muscarinic ligands such as tetrahydropyrimidine-oxadiazoles,tetrahydropyrimidine-thiadiazoles, quinuclidine-thiadiazoles, and thelike.

EXAMPLE 2

Preparation ofmono-[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etherderivatives.

3-(3-Chloro-1,2,5-thiadiazol-4-yl)pyridine (compound 1) was synthesizedfrom 3-pyridinecarboxlaldehyde following published procedures asprovided in Sauerberg et al., Journal of Medicinal Chemistry, 1992, Vol.35, page 2274. Tetra(ethylene glycol)mono ethyl ether was prepared fromthe reaction of tetra(ethylene glycol) with NaH and BrCH₂CH₃ in THF.3-Chloro-4-methoxy-1,2,5-thiadiazole was synthesized by reacting3,4-dichloro-1,2,5-thiadiazole with NaOCH₃.

3-(3-Chloro-1,2,5-thiadiazol-4-yl)pyridine was combined with compound 2(1,12-dodecanediol, tetra(ethylene glycol), or tetra(ethyleneglycol)mono ethyl ether) in the presence of NaH in refluxing THF to givemono-[3-(pyrid-3-yl)-1,2,5-thiadiazol-4-yl]ethers (compounds 3) in40-60% yield.

(For CDD-0304-A, prior to quaternization, the resulting tetra(ethyleneglycol)mono-[3-(pyrid-3-yl)-1,2,5-thiadiazol-4-yl]ether was reactedfurther with 3-chloro-4-methoxy-1,2,5-thiadiazole to give compound 3where R₁ changed to 4-methoxy-1,2,5-thiadiazol-3-yl).

The ethers were treated with excess CH₃l in acetone to yield thequaternary ammonium iodides (compounds 4) in 85-90% yield.

The quaternary salts then were treated with 4 equivalents of NaBH₄ inCH₃OH to yield the free bases (compounds 5) in 30-50% yield.

(For CDD-0299-A and CDD-0303-A, the free bases were converted into thecorresponding acetyl esters (compounds 6) by reacting with excess aceticanhydride in the presence of catalytic anhydrous ZnCl₂ before conversioninto hydrochlorides).

Ethereal HCl then was added into the methylene chloride solution ofcompounds 5 or 6, after crystallization from acetone/ether, and thefinal compounds 7 were obtained in 60-80% yield.

CDD-0297-A:

Formula IIIa

12-[3-(1-Methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yloxy]-1-dodecanolhydrochloride,white powder, m.p. 97-98° C.;

CDD-0299-A:

Formula IIIb

12-[3-(1-Methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yloxy]-1-dodecylacetate hydrochloride, hygroscopic pale yellow powder, m.p. 85-86° C.;

CDD-0300-A:

Formula IIIc

Tetra(ethyleneglycol)mono[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etherhydrochloride, yellow oil;

CDD-0301-A:

Formula IIId

Tetra(ethylene glycol)ethyl[3-1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etherhydrochloride, pale white powder, m.p. 64.5-66° C.;

CDD-0303-A:

Formula IIIe

Tetra(ethyleneglycol)[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etheracetate hydrochloride, hygroscopic white-yellow powder, m.p. 55-55.5°C.;

CDD-0304-A:

Formula IIIf

Tetra(ethyleneglycol)(4-methoxy-1,2,5-thiadiazol-3-yl)[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etherhydrochloride, hygroscopic white-yellow powder, m.p. 35-37° C.

The patents, documents and publications described herein are herebyincorporated by reference.

Having described presently preferred embodiments of the invention, it isto be understood that it may be otherwise embodied within the scope ofthe appended claims.

We claim:
 1. A method of treating a condition selected from pain andAlzheimer's disease comprising administering to a patient in need ofsuch treatment a muscarinic agonistic effective amount of a compound offormula (III):

wherein X is a linkage independently selected from (CH₂)₁₂ or(CH₂CH₂)₄O₃; and wherein R₃ is independently selected from H, CH₂CH₃,COCH₃ or


2. The method of claim 1, wherein the compound is12-[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yloxy]-1-dodecanolhydrochloride.
 3. The method of claim 1, wherein the compound is12-[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yloxy]-1-dodecylacetate hydrochloride.
 4. The method of claim 1, wherein the compound istetra(ethyleneglycol)mono[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etherhydrochloride.
 5. The method of claim 1, wherein the compound istetra(ethyleneglycol)ethyl[3-1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etherhydrochloride.
 6. The method of claim 1, wherein the compound istetra(ethyleneglycol)[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etheracetate hydrochloride.
 7. The method of claim 1, wherein the compound istetra(ethyleneglycol)(4-methoxy-1,2,5-thiadiazol-3-yl)[3-(1-methyl-1,2,5,6-tetrahydropyrid-3-yl)-1,2,5-thiadiazol-4-yl]etherhydrochloride.